1. A fuel nozzle comprising:

a fuel conduit including a first conduit wall including a first circumferentially inner wall surface and a first circumferentially outer wall surface, the first circumferentially inner wall surface defining a fuel passage;

a wind duct that is an annular duct and that includes an inner duct wall and an outer duct wall that define a wind channel adapted for passage of wind for fuel,

wherein:

the air duct is arranged around the fuel duct;

a gap is formed between the inner duct wall of the air duct and the first circumferential outer wall surface.

2. The fuel nozzle of claim 1, wherein:

the gap formed between the inner duct wall of the air duct and the first circumferential outer wall surface is an annular gap.

3. The fuel nozzle of claim 2, wherein:

the fuel pipeline and the wind pipeline are arranged coaxially.

4. The fuel nozzle of claim 1, wherein:

the fuel nozzle further comprises an inlet air pipe, a first inlet is formed in the wall of the outer pipeline of the air pipeline, the first inlet is communicated with the air channel in the tangential direction in the circumferential direction, and the inlet air pipe is communicated with the corresponding first inlet.

5. The fuel nozzle of claim 4, wherein:

the first inlet comprises at least two first inlets equally spaced apart in a circumferential direction.

6. The fuel nozzle of claim 5, wherein:

the at least two first inlets are arranged and adapted such that fuel entering the wind channel via the at least two first inlets enters the wind channel with a wind in a counter-clockwise or clockwise sense.

7. The fuel nozzle of any of claims 1-6, wherein:

the fuel nozzle also comprises a central air pipe;

and the wall of the fuel pipeline is provided with a second inlet, and the central air pipe is communicated with the corresponding second inlet.

8. The fuel nozzle of claim 7, wherein:

the second inlets are communicated with the fuel channels in the tangential direction in the circumferential direction, and the central air pipe is communicated with the corresponding second inlets.

9. The fuel nozzle of claim 8, wherein:

the second inlet comprises at least two second inlets equally spaced apart in the circumferential direction.

10. The fuel nozzle of claim 9, wherein:

the at least two second inlets are arranged and adapted such that fuel entering the fuel passage via the at least two second inlets enters the fuel passage with a wind in a counter-clockwise or clockwise sense.

11. The fuel nozzle of claim 7, wherein:

the fuel duct includes an extension portion extending to an outside of the wind duct, and the second inlet is provided at the extension portion.

12. The fuel nozzle of claim 7, wherein:

the central air pipe is made of temperature-resistant and wear-resistant materials.

13. The fuel nozzle of claim 1, wherein:

the fuel pipeline is made of temperature-resistant and wear-resistant materials.

14. The fuel nozzle of any of claims 1-13, wherein:

the air pipeline is a secondary air pipeline.

15. The fuel nozzle of any of claims 1-13, wherein:

the fuel nozzle is suitable for fuel flow with the temperature not lower than 700 ℃.

16. A combustion apparatus, comprising:

a combustion space; and

the fuel nozzle of any one of claims 1-15, in communication with the combustion space.

17. The combustion apparatus of claim 16, wherein:

the combustion space is a hearth, and the fuel nozzles are positioned at the bottom, the side part or the top of the hearth; or

The combustion space is the combustion space of an industrial kiln.

18. The combustion apparatus of claim 17, further comprising:

a fuel pretreatment device, the fuel nozzle being located between the combustion space and the fuel pretreatment device.

19. The combustion apparatus of claim 18, wherein:

the fuel pretreatment equipment is circulating fluidized bed pretreatment equipment.

20. A combustion control method of a combustion apparatus according to any one of 16-19, the combustion apparatus being a boiler, the method comprising the steps of:

and simultaneously, adjusting the rotation intensity of secondary air and the mixed rotation intensity of central air and fuel to form inner layer flame mainly based on central air combustion supporting and gasification reaction and outer layer flame mainly based on secondary air combustion supporting and gasification reaction, wherein high-temperature preheating fuel is arranged between the double flame interlayers.

Background

The pulverized coal preheating combustion technology is a high-efficiency technology capable of realizing direct ultralow NOx emission control of pulverized coal combustion. The method is characterized in that a solid fuel fluidization pretreatment unit is usually adopted, high-temperature preheating gas-solid fuel (the temperature can reach more than 700 ℃ usually, such as 800-1000 ℃) generated by coal powder preheating is carried out through the pretreatment unit, and air distribution is reasonably and deeply organized through a high-temperature fuel nozzle, so that ultralow NOx emission of the coal powder is realized.

In the prior art, the pulverized coal is conveyed into a hearth mainly by preheating primary air by a tail flue air preheater to form high-temperature primary air, and the high-temperature primary air exchanges heat with the pulverized coal in a gas-powder mixing mode in the process of conveying the pulverized coal, so that the temperature of the pulverized coal can reach about 60-140 ℃ when the pulverized coal is conveyed into a nozzle. In the aspect of combustion organization, the existing burner nozzle structure is only set for the temperature of 60-140 ℃, and cannot be applied to the preheating combustion technology due to too large working temperature difference. Especially, the temperature of the high-temperature fuel is further increased (for example, 1000-1200 ℃) by burning after the high-temperature fuel is contacted with oxygen, the existing nozzle is easy to generate high-temperature ablation and pipeline softening deformation, and the flame structure at the outlet of the nozzle is seriously deviated when the nozzle is serious, so that the operation safety and the effect of burning the structure are influenced.

Disclosure of Invention

To alleviate or solve at least one aspect or at least one point of the above-mentioned problems, the present invention is directed.

According to an aspect of an embodiment of the present invention, there is provided a fuel nozzle including:

a fuel conduit including a first conduit wall including a first circumferentially inner wall surface and a first circumferentially outer wall surface, the first circumferentially inner wall surface defining a fuel passage;

a wind duct that is an annular duct and that includes an inner duct wall and an outer duct wall that define a wind channel adapted for passage of wind for fuel,

wherein:

the air duct is arranged around the fuel duct;

a gap is formed between the inner duct wall of the air duct and the first circumferential outer wall surface.

According to another aspect of an embodiment of the present invention, a combustion apparatus is proposed, comprising a combustion space and a fuel nozzle as described above.

According to still another aspect of an embodiment of the present invention, there is provided a combustion control method of the above combustion apparatus, including the steps of: and simultaneously, adjusting the rotation intensity of secondary air and the mixed rotation intensity of central air and fuel to form inner layer flame mainly based on central air combustion supporting and gasification reaction and outer layer flame mainly based on secondary air combustion supporting and gasification reaction, wherein high-temperature preheating fuel is arranged between the double flame interlayers.

Drawings

FIG. 1 is a cross-sectional schematic view of a fuel nozzle according to an exemplary embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view A-A of the fuel nozzle of FIG. 1;

FIG. 3 is a schematic cross-sectional view taken along line B-B of the fuel nozzle of FIG. 1;

fig. 4 is a schematic structural view of a combustion apparatus according to an exemplary embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as limiting the invention. In the present invention, the same reference numerals denote the same or similar components.

FIG. 1 is a schematic cross-sectional view of a fuel nozzle according to an exemplary embodiment of the present invention, FIG. 2 is a schematic cross-sectional view taken along A-A of the fuel nozzle of FIG. 1, and FIG. 3 is a schematic cross-sectional view taken along B-B of the fuel nozzle of FIG. 1.

In one embodiment of the invention, the fuel nozzle can be a high-temperature preheating fuel ultra-low NOx nozzle, and the fuel nozzle can be applied to a pulverized coal preheating combustion technology.

Fig. 1 exemplarily shows a cross-sectional structure of the fuel nozzle, which includes a primary air fuel pipeline 1 and an air pipeline 2 in sequence from inside to outside, wherein the fuel pipeline 1 may be a high temperature preheating fuel pipeline 1, and the air pipeline may be a secondary air pipeline 2. A secondary air duct 2 is provided around the fuel duct 1.

In the present invention, as shown in fig. 1, the overfire air duct 2 comprises an inner duct wall 21 and an outer duct wall 22 (schematically, wherein the thickness of the duct walls is not shown), the inner duct wall 21 and the outer duct wall 22 defining a wind channel therebetween.

As shown in fig. 2, the secondary air is connected to the secondary air duct 2 by two tangential inlet pipes 3, so that the secondary air is rotated counterclockwise after entering the secondary air duct.

In the present invention, the outer duct wall 22 of the overfire air duct 2 is provided with at least one first inlet which communicates tangentially with the overfire air duct in the circumferential direction, the tangential inlet duct 3 communicating with a corresponding first inlet. In a further embodiment, the first inlet comprises at least two first inlets equally spaced apart in the circumferential direction. The at least two first inlets are arranged and adapted such that fuel entering the wind channel via the at least two first inlets enters the wind channel with a wind in a counter-clockwise or clockwise sense.

According to an exemplary embodiment of the invention, as shown in fig. 3, the central wind inlet duct 4 also adopts a tangential entry arrangement instead of placing the central wind inlet duct 4 axisymmetrically directly into the fuel channel 1.

As shown in fig. 3, the central wind inlet pipe 4 communicates with the fuel passage of the fuel pipe 1. As can be appreciated, the duct wall of the fuel duct 1 is provided with a second inlet, with the central wind inlet duct 4 communicating with a corresponding second inlet. Alternatively, the second inlets communicate tangentially with the fuel channel 1 in the circumferential direction, and the central wind inlet duct 4 communicates with the corresponding second inlets. Still further optionally, the second inlet comprises at least two second inlets equally spaced apart in the circumferential direction. In one embodiment of the invention, the at least two second inlets are arranged and adapted such that fuel entering the fuel channel via the at least two second inlets enters the fuel channel 1 with a counterclockwise or clockwise turning. The rotating central wind is fed into the fuel channel 1 so that the central wind and the spinning (if any) fuel stream in the fuel channel are intensively mixed.

In one embodiment of the invention, the central air volume ratio is small, and blended and partially gasified combustion is formed in the fuel pipeline 1 of the fuel nozzle, which is beneficial to quickly carrying out secondary gasification on premixed fuel injected from the fuel nozzle subsequently, and the secondary gasification deeply reduces the NOx emission of the fuel and realizes efficient combustion.

In an exemplary embodiment according to the present invention, the fuel pipeline 1 and the annular secondary air pipeline 2 are both in a central axis symmetrical form, and a gap exists between the fuel pipeline 1 and the secondary air pipeline 2, and the pipeline gap is favorable for high temperature thermal expansion, and prevents the pipeline deformation or stress pulling crack at the welding position. In a further embodiment, the gap formed between the secondary air duct and the outer wall surface of the fuel duct 1 is an annular gap, and in a further embodiment, the fuel duct 1 and the secondary air duct 2 are arranged coaxially, so that the annular gap can be an annular gap of equal width. In an exemplary embodiment according to the present invention, the intermediate pipe of the fuel nozzle is made of a refractory and wear-resistant castable material, which prevents a high-temperature preheating fuel flow (with a temperature not lower than 700 ℃, for example, in the range of 800-. In an alternative embodiment, the central air inlet pipe 4 opens tangentially into the lower section of the fuel pipe 1, i.e. the part of the fuel pipe 1 extending outside the secondary air pipe 2, with a central axis symmetry around the circumference, as shown in fig. 1.

In an exemplary embodiment according to the present invention, as shown in fig. 4, the pulverized coal enters the circulating fluidized bed 5 to perform fluidized preheating gasification combustion modification, and the fluidized preheating process is to maintain the heat balance of the circulating fluidized bed through partial combustion and partial gasification of solid pulverized coal particles.

During the preheating combustion of the pulverized coal, the problems of abrasion of the central air inlet pipe 4 of the fuel nozzle in the fuel pipeline 1 and mixing of the central air inlet pipe and the fuel nozzle need to be prevented, and the fuel nozzle is prevented from being deformed due to high-temperature ablation.

According to an exemplary embodiment of the invention, the high-temperature preheating fuel and the central air can be efficiently and reasonably blended and mixed, so that the central air and the high-temperature preheating fuel are fully mixed and combusted, and a secondary strong gasification nitrogen reduction reaction area in a high-temperature area of the high-temperature preheating fuel is formed.

According to an exemplary embodiment of the invention, the fuel jets may be arranged at the side and top or bottom of the boiler. The arrangement mode at the side part of the hearth can also adopt the opposite impact arrangement.

According to an exemplary embodiment of the present invention, the tangential inlet to secondary air (i.e. the first inlet) structure of the fuel nozzle in fig. 2 may employ two inlet pipes 3, or three or four or even more inlet pipes arranged at equal intervals in the circumferential direction.

According to an exemplary embodiment of the invention, the central wind inlet duct 4 in fig. 3 communicates with the fuel channel 1 in a tangential manner, two central wind inlet ducts 4 may be used, or three or even more central wind inlet ducts 4 may be used, which may be arranged at equal intervals in the circumferential direction, each central wind inlet duct 4 being arranged to maintain a uniform turning direction.

According to an exemplary embodiment of the invention, the fuel nozzles can be arranged at the bottom of the furnace, arranged at the side and arranged at the top, a single fuel nozzle can be adopted, and three nozzles or four nozzles with axial symmetry can be adopted, which can be determined according to the capacity of the hearth, the sectional area of the bottom, the fuel mixing effect, the flame fullness and the single nozzle thermal power.

The fuel mentioned in the invention can be coal powder, and can also be replaced by solid wastes such as gasified fine fly ash, pyrolysis semicoke, coal gangue and the like.

The technical scheme of the invention is different from the prior art in at least one of the following ways:

(1) the fuel is suitable for different types, and the fuel used in the technical scheme is high-temperature semicoke (Char) and coal gas (CH)₄,H₂,CO,N₂Etc.) whereas the fuel used in the nozzle of the prior art solution is pulverized coal powder.

(2) The temperature of the fuel is different, the temperature range of the fuel used in the technical scheme is not lower than 700 ℃, for example, 800-1000 ℃, and the mixing temperature range of the primary air-conveying powder of the fuel nozzle in the prior art is 60-140 ℃.

(3) The fuel has different characteristics, the fuel of the technical scheme is that pulverized coal fuel needs to be subjected to fluidized gasification combustion pretreatment at the temperature of not less than 700 ℃, for example, at the temperature of 800-. Therefore, the technical scheme can not be used for the cold pulverized coal combustion in the prior art.

(4) The central air pipe adopted by the technical scheme is a temperature-resistant and wear-resistant casting material pipeline, the temperature of the fuel is not lower than 700 ℃ through high-temperature preheating, such as 800-1000 ℃, and a stainless steel pipe adopted by the central air pipe in the prior art is easy to abrade, leak and deform at high temperature, so that high-temperature fuel flame deflection, incomplete combustion and high NOx emission are caused.

According to an exemplary embodiment of the invention, aiming at the problem of abrasion of the high-temperature preheating fuel pipeline, the technical scheme is that the high-temperature preheating fuel pipe is made of a temperature-resistant wear-resistant material instead of a steel structure, so that scouring, abrasion and high-temperature ablation deformation of the high-temperature preheating fuel on the wall surface of the high-temperature preheating fuel pipeline are effectively prevented.

According to an exemplary embodiment of the present invention, a central air inlet pipe 4 is used to enter the fuel pipe 1 tangentially for the problem of difficulty in blending the central air and the high temperature preheated fuel. If the mixing of the central air and the high-temperature preheated fuel in the nozzle pipeline is enhanced and the mixing uniformity is enhanced, the fuel and the central air can be fully mixed in advance, so that the temperature required by secondary forced gasification in the outlet area of the subsequent nozzle can be effectively increased.

According to an exemplary embodiment of the present invention, the overfire air inlet pipe 3 is provided, while the main overfire air pipe is the overfire air pipe 2 formed by the inner pipe wall 21 and the outer pipe wall 22 which are resistant to temperature and wear, the overfire air pipe is arranged around the fuel pipe 1, and in a further embodiment, a gap is formed between the overfire air pipe 2 and the fuel pipe 1, which can avoid or alleviate the problems of sealing, welding and pulling crack of the contact area between the pipe and the overfire air bellows of the original common fuel pipe 1.

According to an exemplary embodiment of the invention, the central wind inlet duct 4 enters the fuel flow tangentially.

The two schemes combine to produce the effect: through the combination of the two structural schemes of the secondary air structure and the central air, the central air tangentially enters the fuel pipeline, so that a small amount of central air and high-temperature fuel are fully mixed, the temperature of the high-temperature fuel is further raised from about 800 ℃ to 950 ℃ to 1100 ℃ when the high-temperature fuel is sprayed out of a fuel nozzle, the temperature rise is favorable for enhancing the gasification reaction activity promotion of the small amount of central air on the high-temperature preheated fuel, the further release of fuel nitrogen into nitrogen is accelerated, and the combustion effect after the fuel nitrogen leaves the fuel nozzle is ensured.

According to an exemplary embodiment of the invention, the rotation intensity of the secondary air and the rotation intensity of the mixture of the central air and the fuel can be adjusted simultaneously in a matching manner so as to realize controllable propagation of the jet rotating flame, which is more beneficial to forming inner layer flame mainly based on combustion supporting and stronger gasification reaction of the central air and outer layer flame mainly based on combustion supporting and stronger gasification reaction of the secondary air, and the double-flame interlayer is high-temperature preheating fuel, and gradually rises along the air flow to gradually mix the interface combustion reaction of the flame, so that the fuel nitrogen is more controllably and orderly combusted and released.

Based on the above, the invention provides the following technical scheme:

1. a fuel nozzle comprising:

a fuel conduit including a first conduit wall including a first circumferentially inner wall surface and a first circumferentially outer wall surface, the first circumferentially inner wall surface defining a fuel passage;

a wind duct that is an annular duct and that includes an inner duct wall and an outer duct wall that define a wind channel adapted for passage of wind for fuel,

wherein:

the air duct is arranged around the fuel duct;

a gap is formed between the inner duct wall of the air duct and the first circumferential outer wall surface.

2. The fuel nozzle according to claim 1, wherein:

the gap formed between the inner duct wall of the air duct and the first circumferential outer wall surface is an annular gap.

3. The fuel nozzle according to claim 2, wherein:

the fuel pipeline and the wind pipeline are arranged coaxially.

4. The fuel nozzle according to claim 1, wherein:

the fuel nozzle further comprises an inlet air pipe, a first inlet is formed in the wall of the outer pipeline of the air pipeline, the first inlet is communicated with the air channel in the tangential direction in the circumferential direction, and the inlet air pipe is communicated with the corresponding first inlet.

5. The fuel nozzle according to 4, wherein:

the first inlet comprises at least two first inlets equally spaced apart in a circumferential direction.

6. The fuel nozzle of claim 5, wherein:

the at least two first inlets are arranged and adapted such that fuel entering the wind channel via the at least two first inlets enters the wind channel with a wind in a counter-clockwise or clockwise sense.

7. The fuel nozzle according to any one of claims 1-6, wherein:

the fuel nozzle also comprises a central air pipe;

and the wall of the fuel pipeline is provided with a second inlet, and the central air pipe is communicated with the corresponding second inlet.

8. The fuel nozzle of claim 7, wherein:

the second inlets are communicated with the fuel channels in the tangential direction in the circumferential direction, and the central air pipe is communicated with the corresponding second inlets.

9. The fuel nozzle of claim 8, wherein:

the second inlet comprises at least two second inlets equally spaced apart in the circumferential direction.

10. The fuel nozzle of claim 9, wherein:

the at least two second inlets are arranged and adapted such that fuel entering the fuel passage via the at least two second inlets enters the fuel passage with a wind in a counter-clockwise or clockwise sense.

11. The fuel nozzle of claim 7, wherein:

the fuel duct includes an extension portion extending to an outside of the wind duct, and the second inlet is provided at the extension portion.

12. The fuel nozzle of claim 7, wherein:

the central air pipe is made of temperature-resistant and wear-resistant materials.

13. The fuel nozzle according to claim 1, wherein:

the fuel pipeline is made of temperature-resistant and wear-resistant materials.

14. The fuel nozzle of any one of claims 1-13, wherein:

the air pipeline is a secondary air pipeline.

15. The fuel nozzle of any one of claims 1-13, wherein:

the fuel nozzle is suitable for fuel flow with the temperature not lower than 700 ℃.

16. A combustion apparatus, comprising:

a combustion space; and

the fuel nozzle of any one of claims 1-15, in communication with the combustion space.

17. The combustion apparatus of claim 16, wherein:

the combustion space is a hearth, and the fuel nozzles are positioned at the bottom, the side part or the top of the hearth; or

The combustion space is the combustion space of an industrial kiln.

18. The combustion apparatus of claim 17, further comprising:

a fuel pretreatment device, the fuel nozzle being located between the combustion space and the fuel pretreatment device.

19. The combustion apparatus of claim 18, wherein:

the fuel pretreatment equipment is circulating fluidized bed pretreatment equipment.

20. A combustion control method of a combustion apparatus according to any one of 16-19, the combustion apparatus being a boiler, the method comprising the steps of:

and simultaneously, adjusting the rotation intensity of secondary air and the mixed rotation intensity of central air and fuel to form inner layer flame mainly based on central air combustion supporting and gasification reaction and outer layer flame mainly based on secondary air combustion supporting and gasification reaction, wherein high-temperature preheating fuel is arranged between the double flame interlayers.

In the present invention, each numerical range, in addition to the endpoints explicitly indicated as being not inclusive, may be the endpoints, and may be the median of each numerical range, and all of these are within the scope of the present invention.

Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments and combinations of elements without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.